SURROGATE MARKERS CORE PROJECT SUMMARY (See instructions): Neurocognitive impairment in HIV-infected individuals remains a significant problem despite antiretroviral therapy. There is a critical need for surrogate markers that can be used to predict cognitive impairment and to monitor the effects of antiretroviral, or neuroprotective therapy in HIV-infected individuals. The primary goals of the Surrogate Marker / Pharmacokinetic Core will be to: 1) Assist in the development and monitoring of surrogate markers for HIV-associated neurocognitive disorders (HAND). 2) To provide mentorship and consultation for Neuro-AIDS researchers in the development of clinically useful surrogate markers for HAND and to validate these as predictive and associative markers for cognitive impairment and as surrogate markers for therapeutic effectiveness. An additional task ofthe core will be to assist in the development of small molecule therapeufics by providing consultation on pharamcokinetic/pharmacodynamic considerations for drug development, and conducting pharmacokinetic and analysis of potential drugs and drug metabolites.